A 10fold stretchfactor photonic TimeStretch AnalogtoDigital Converter (TSADC) system for a 5 GHz radiofrequency signal is achieved.By adopting the photonic time stretch scheme to compress the bandwidth of RadioFrequency,the effective analog bandwidth and effective sampling rate of the posterior electronic AnalogtoDigital Conversion were improved.The dispersioninduced power penalty of the stretched signal as well as the modulationinduced harmonic distortion were analyzed and simulated.The theoretical analysis and experimental results indicate that the SignaltoNoise And Distortion ratio of the photonic timestretch process is high enough to maintain the high effective number of bit of the posterior electronic AnalogtoDigital Conversers in the bandwidth of 0~5 GHz.In addition,the designed TSADC system can achieve an effective analog bandwidth of 8 GHz and an effective sampling rate of 200 GS/s.